Tamper evident cap wtih wavy ring seal

ABSTRACT

There is a tamper evident cap of the type having a detachable annular band 7. The band is shaped to push fit over a shoulder 18 on the neck of a container 4 during initial sealing of the cap on the container. Subsequently the band 7 breaks away and stays with the container on removal of the cap to provide evidence of the removal. There is a shoulder engaging edge 13 of the band which is contoured to form resiliently deflectable undulations around the circumference of the band to engage over a range of shoulder diameters.

FIELD OF THE INVENTION

[0001] This invention relates to tamper evident caps. More particularlyit discloses an improved cap of the type having a detachable tamperevident band.

BACKGROUND TO THE INVENTION

[0002] One known type of tamper evident cap hits an annular band whichis attached around the bottom by frangible links such as a series ofnarrow ribs. The band is adapted to push over a shoulder moulded arounda container neck during initial sealing thereof but subsequently breakaway and stay with said container when it is opened for the first time.A band which is separated from the cap therefore provides readilyvisible evidence that the container has been previously opened. Tamperevident caps provide consumers with assurance that the products theychoose off supermarket shelves have not been interfered with.Difficulties have been encountered with the fitting of existing capshowever due to uncontrollable variations in the shoulder diameter onmoulded containers. In order to work the plain locking ring edges ofcurrent tamper evident bands (illustrated for example as the straightline free edge of flap 34 in prior art Australian patent 591512) musthave a diameter which is within about ±0.6 mm per side of the meanshoulder diameter. With moulded glass bottles however the uncontrollablevariation from the mean shoulder diameter can be as much ±1 mm. Thisvariation causes either problems with the initial fitting of bands overshoulders at the outer tolerance limit or, with those shoulders at theinner tolerance limit, the failure of band separation during subsequentremoval of the cap. Consequently with some moulded bottles the bandsbreak during initial fitting and with others the bands subsequently comeoff and on freely with the caps. In the latter case the problem isexacerbated with moulded glass bottles as the shoulder edges cannot bemade sharp and are therefore difficult to grip. In either case howeverno reliable evidence of tampering is provided to the consumer.

SUMMARY OF THE INVENTION

[0003] It is therefore an object of this invention to ameliorate theaforementioned disadvantages and accordingly a tamper evident cap of thetype having a detachable annular band is disclosed, said band beingadapted to push fit over a shoulder on the neck of a container duringinitial sealing of said cap thereon and to subsequently break away andstay with said container on removal of the cap to provide evidence ofsaid removal wherein a shoulder engaging edge of the band is contouredto form resiliently deformable undulations around the circumference ofsaid band to engage over a range of shoulder diameters.

[0004] Preferably but not essentially said waves are spaced at about 10degrees around the circumference of said band.

[0005] It is further preferred that said edge is adapted to invert intothe cap during initial sealing of said cap on the container.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The currently preferred embodiments of the invention will now bedescribed with reference to the attached drawings in which:

[0007]FIG. 1 is a cross-sectional view of a tamper evident ring sealplain cap according to a first embodiment of this invention beforefitting onto a container.

[0008]FIG. 2 is a view similar to FIG. 1 but with the edge invertedafter fitting onto the container,

[0009]FIG. 3 is a cross-sectional view along the lines A-A of FIG. 1,

[0010]FIG. 4 shows a partial cross-sectional view of a child resistanteyedropper cap constructed according to a second embodiment of thisinvention, and

[0011]FIG. 5 is a cross-sectional view of child resistant wadded capconstructed according to a third embodiment of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0012] Referring first to FIGS. 1, 2 and 3 the cap is provided withscrew threads 1 around the inside of the skirt 2 to mate withcorresponding threads 3 on a moulded medicine bottle 4. There are alsoflexible concentric flanges 5 formed inside the top of the cap whichengage the upper lip 6 of the bottle to provide a fluid-tight seal. Inaccordance with this invention there is an annular tamper evident band 7around the base of the skirt 2. The band is attached by means offrangible angled ribs 8 which extend between an upper band edge 9 asshown and the bottom 10 of said skirt. The opposite lower portion of theband as best shown in FIG. 1 is shaped into a locking ring 7A of reducedthickness and is connected to the main band portion 7 along a plastichinge line 11 interrupted by spaced apart slits 12. In accordance withthis invention the free edge 13 of this locking ring 7A is shaped toform undulations or waves which extend around the circumference of saidring. Although the invention is not limited to any specific dimensions,with this particular embodiment which is intended to fit a mean shoulderdiameter of say 25 mm the inside diameter of the, band may be 27 mm, theheight of the undulations may be about 1.5 mm and said undulations maybe spaced about 10 degrees apart around the circumference of the ring.The aforementioned slits 12 are also preferably positioned to correspondwith the peaks 15 of the undulations as best shown in FIG. 3. Each slitpreferably also subtends an angle of about 10 degrees.

[0013] The initial configuration of the cap as moulded with the ring 7Aextending downwardly is shown in FIG. 1. This ring subsequently flipsupwardly about the hinge line 11 upon push fitting and screwing of thecap onto the threaded bottle neck 16 as shown in FIG. 2. The undulatingedge 13 is thus directed upwardly so that the peaks 15 seat in a recess17 formed under the shoulder 18. The edge 13 thereby secures the lockingring onto the neck of the bottle so that subsequent removal of the capbreaks the angular ribs and separates the band to stay with the bottleand provide evidence of the opening

[0014] The forces exerted by the ring 7A on the band 7 during theaforementioned assembly process are resisted by support pods 18A formedaround the upper edge 9 of Said band. In particular the shear forcesbetween the skirt 2 and the band 7 are resisted by drive dogs 18Breacting against these pads 18A so that the angled ribs 8 do notseparate.

[0015] It has been found by the inventor that by virtue of the wavy orundulating shape described above the locking ring works over a widerange of dimensional variation which on the aforementioned mean shoulderdiameter may be ±5 mm. This range is much greater than prior art plainedged rings can function with. Even with those bottles having thesmallest allowable shoulder diameter the inner peaks 15 of the invertedring 7A after passing over said shoulder spring back sufficiently tosecure the band against removal. With those shoulders having the largestallowable diameter at the other end of the tolerance range the peaks 15resiliently compress enough for the band to fit without prematurefracture. In this latter case the slits 12 have been found to assist thecompression of the ring.

[0016] With the second and third embodiments of FIGS. 4 and 5 a lockingring according to this invention is shown fitted to child resistantcaps. The main components of these caps which correspond in function tothose of FIGS. 1 to 3 are indicated by the same numbers which howeverare primed (″) and (′″) to distinguish them. These caps have threadedskirts fitted within cowlings indicated respectively as 19, 20 and 21,22. The cowlings 20, 22 are movable relative to said skirts betweenfirst positions at which the cowlings engage lugs 23, 24 on the skirtswhen turned in a rotational direction to screw the skirts onto acontainer such as a bottle and a second position at which the skirts areengaged by the cowlings in the opposite rotational direction to enablethe skirts to be unscrewed. There are also cam surfaces 25, 26 on thecowlings which engage inclined shoulders 27, 28 on the skirts to biasethe cowlings to the first position. The second embodiment of FIG. 4 alsohas an eyedropper 29 fitted.

[0017] It will thus be appreciated that this invention at least in theform of the embodiments disclosed provide a novel and useful improvementin the construction of tamper evident caps. Initial trials have shownthat one size of tamper evident band constructed according to thisinvention can work over a much wider range of shoulder diametervariations than prior art bands. This reduces manufacturing costs andproduces a better performing product. Clearly however the examplesdescribed are only the currently preferred forms of the invention and awide variety of modifications may be made which would be apparent to aperson skilled in the art. For example the design of the tamper evidentband as well as the number, shape and configuration of the undulationsin the locking ring may be changed following further development by theinventor. Also, while it is currently preferred to mould the cap frompolypropylene other suitable materials may be used.

[0018] Expressions such as “upper”, “lower”, “bottom” and “downwardly”etc. refer to the caps in one position of use as illustrated and are notto be read as necessarily limiting.

1. A tamper evident cap of the type having connected thereto adetachable annular band, said band being shaped to push fit over ashoulder on the neck of a container during initial sealing of said capthereon and to subsequently break away and stay with said container onremoved of the cap to provide evidence of said removal wherein ashoulder engaging edge of the band is contoured to form resilientlydeformable undulations around the circumference of said band to engageover a range of shoulder diameters.
 2. The tamper evident cap as claimedin claim 1 wherein the band includes a main band portion and it lockingring with said shoulder engaging edge being a free edge of said lockingring.
 3. The tamper evident cap as claimed in claim 2 wherein before theinitial sealing of the cap on the container the locking ring extendsdownwardly and subsequently inverts about a hinge line during saidsealing so that the shoulder engaging edge is directed upwardly toengage under the shoulder.
 4. The tamper evident cap as claimed in claim3 wherein the hinge line connects the locking ring to the main bandportion.
 5. The tamper evident cap as claimed in claim 4 wherein saidhinge line is interrupted by spaced apart slits.
 6. The tamper evidentcap as claimed ire claim 5 wherein said slits are positioned tocorrespond with peaks of said undulations to assist compression of thelocking ring as said locking ring passes over said shoulder duringinitial sealing.
 7. The tamper evident cap as claimed in claim 6 whereinsaid band is detachably connected to a skirt of said cap by frangibleangled ribs which extend between an upper edge of said band and a bottomedge of said skirt.
 8. The tamper evident cap as claimed in claim 7wherein shear forces acting between said skirt and bend during initialsealing are resisted by drive dogs on the lower edge of said skirtreacting against support pads on the upper edge of said band.
 9. Thetamper evident cap as claimed in claim 8 wherein said undulations arespaced apart by about 10 degrees around the circumference of said ring.10. The tamper evident cap as claimed in claim 9 wherein said cap is achild resistant cap which includes a cowling fitted over the skirt andmovable relative to said skirt between a first position wherein saidcowling engages lugs on said skirt when turned in a rotational directionto screw said skirt onto said container and a second position at whichsaid skirt is engaged by said cowling in the opposite rotationaldirection to enable said skirt to be unscrewed and a cam surface on oneof said skirt and cowling which engages an inclined shoulder on theother one of said skirt and cowling whereby said cowling is biased tosaid first position.